I suppose they prefer the freedom than the hutch? I know I sometimes have to usher mine under cover when it starts raining, but to give them their due rain is a new thing to them!

Yes, I think they prefer the freedom of the run. I have now had the experience of a total of four rabbits that I have adopted and they were all originally kept in a hutch. After I adopted them I gave them a hutch and run. Without exception this is what happened: the first week they stayed mostly in the hutch; in their new environment they were a bit scared to move about. After a few days they started exploring the run but still ran back to the hutch when they saw something scary. After about a week, they moved into the run on pretty much a permanent basis and effectively abandoned the hutch. It doesn't matter how cold it is, they don't go up any more. Maybe when something very scary happens but only then.

Mine spend most of winter sat in their run despite easy access to the playhouse. The only buns I ever move into the garage are the group with an elderly bun and an arthritic bun, but its not really necessary for healthy bunnies unless the weather is extream.

I Suffer From Multiple Rabbit Syndrome
(Because One Rabbit Is Never Enough!)

Mine spend most of winter sat in their run despite easy access to the playhouse.

Same here. Whenever I go out to check on them during the winter months - it could be late at night, with icy wind blowing, I'm dressed like I'm going on an arctic expedition - I invariably find them sitting on the ground and they just look at me like "what's the problem, mate?". I do hope they would have the sense to hide in the hutch if they found it unbearable but so far it hasn't happened.

How I keep my rabbit warm during the winter

I have a double dog kennel for my one rabbit Clover. I have laid down chicken wire so she could not dig out. Also I put a roll of 2 foot high chicken wire around the whole dog kennel itself so a cat or raccoon could not reach through and perhaps grab her if she was resting along the side area of the kennel. In the kennel area over the chicken wire I put several inches of dirt and sowed grass. Inside this dog kennel I built her a rabbit hutch which is 6 foot by 4 foot. The hutch itself is divided into several areas which includes a bathroom area where a cat litter box sits lined with a puppy pad then covered with newspaper and then timothy hay on top of that. (This gets changed 3 times a week even though she does not potty in it). She also has a sitting area with a rubberific brown paver I got from Lowes lawn and garden section. She LOVES sitting on them. (I have several of them scattered throughout her kennel outside her hutch). She has two high sitting boards if she would like to jump up and sit. One of these sitting boards led into a back room where I have set up a heater for her during the winter months. The backroom hole was cut out like a “mouse hole” big enough for her to go through and I place an old t-shirt cut to size and stapled above the hole as a flap to keep heat in that area. She had no trouble pushing through the flap to access the back room area. The heater consists of a half concrete block that sits on a tile base and inside the block I have a ceramic light socket fixture which sits on the tile base inside the block. I use a 90 watt bulb in this socket. I then took a 9x9 square cake pan and drilled a row of holes on all sides of the pan and then placed this upside down over the top of the concrete block and then placed a couple bricks on top of that to secure it. I drilled a hole through the outside wall of this hutch area and put the wire through and pushed this heater back close enough to the wall so she could not get to the wire to chew on it. I placed steel wool around the hole area to keep mice from entering. The wire came out and up over the top of her hutch and plugged into an outlet I had fixed above her hutch. It works perfectly. Her heated water bowl (bought one especially for rabbits) is also done this same way coming out of the hutch and plugging in on top of her hutch. I only use this IF it gets below 20 outside. The other things I have for heat is a heater I bought from https://www.sweeterheater.com . I bought the 11X11 overhead one. I placed this one on the sitting board upright towards the outside end and secured it and ran the wire out through the side of her cage and up to the top of the roof where it plugged in up there into a thermo-cube. This thermo-cube automatically comes on when the temps gets below 35 and auto shuts off when the temp reaches 45. So the heater automatically comes on and goes off on its own. This is perfect. Her cage is up from the ground about 2 ½ feet and around the bottom of her hutch I nailed up boards to the hutches legs and made her a sandbox under there. She loves to play and dig and push the sand around. When I made the hutch I made one area into a foyer and this has a cat door installed. So she can go and come as she pleases. She loves her cat door. So she can go out and play and when she gets cold she will go in and warm up. She also has an outside potty area where I took a tote and turned it on its side and placed a cat litter box in there. She uses that all the time and never uses the one in her hutch. She just eats her timothy hay in that one. Her kennel area is set up with all kinds of fun things to do and explore. I even have an old tree truck turned upside down that she loves to play in. She has her own sidewalk which makes it nice for me and solar lights. I have even set up a security camera to her kennel so I am able to watch her from the house. I know, she has me wrapped around her little tail!!! LOL